docs: def dP_venturi_tube(D, Do, P1, P2):
      r'''Calculates the non-recoverable pressure drop of a venturi tube 
      differential pressure meter based on the pressure drop and the geometry of 
      the venturi meter.
      
      .. math::
          \epsilon =  \frac{\Delta\bar w }{\Delta P}
          
      The :math:`\epsilon` value is looked up in a table of values as a function
      of beta ratio and upstream pipe diameter (roughness impact).
          
      Parameters
      ----------
      D : float
          Upstream internal pipe diameter, [m]
      Do : float
          Diameter of venturi tube at flow conditions, [m]
      P1 : float
          Static pressure of fluid upstream of venturi tube at the cross-section 
          of the pressure tap, [Pa]
      P2 : float
          Static pressure of fluid downstream of venturi tube at the
           cross-section of the pressure tap, [Pa]
  
      Returns
      -------
      dP : float
          Non-recoverable pressure drop of the venturi tube, [Pa]
  
      Notes
      -----
      The recoverable pressure drop should be recovered by 6 pipe diameters 
      downstream of the venturi tube.
      
      Note there is some information on the effect of Reynolds number as well
      in [1]_ and [2]_, with a curve showing an increased pressure drop
      from 1E5-6E5 to with a decreasing multiplier from 1.75 to 1; the multiplier
      is 1 for higher Reynolds numbers. This is not currently included in this
      implementation.
      
      Examples
      --------
      >>> dP_venturi_tube(D=0.07366, Do=0.05, P1=200000.0, P2=183000.0)
      1788.5717754177406
      
      References
      ----------
      .. [1] American Society of Mechanical Engineers. Mfc-3M-2004 Measurement 
         Of Fluid Flow In Pipes Using Orifice, Nozzle, And Venturi. ASME, 2001.
      .. [2] ISO 5167-4:2003 - Measurement of Fluid Flow by Means of Pressure 
         Differential Devices Inserted in Circular Cross-Section Conduits Running
         Full -- Part 4: Venturi Tubes.
      '''
      # Effect of Re is not currently included
      beta = Do/D
      epsilon_D65 = interp(beta, venturi_tube_betas, venturi_tube_dP_high)
      epsilon_D500 = interp(beta, venturi_tube_betas, venturi_tube_dP_low)
      epsilon = interp(D, D_bound_venturi_tube, [epsilon_D65, epsilon_D500])
      return epsilon*(P1 - P2)